Characteristic function-based inference for GARCH models with heavy-tailed innovations

We consider estimation and goodness-of-fit tests in GARCH models with innovations following a heavy-tailed and possibly asymmetric distribution. Although the method is fairly general and applies to GARCH models with arbitrary innovation distribution, we consider as special instances the stable Paretian, the variance gamma, and the normal inverse Gaussian distribution. Exploiting the simple structure of the characteristic function of these distributions, we propose minimum distance estimation based on the empirical characteristic function of properly standardized GARCH-residuals. The finite-sample results presented facilitate comparison with existing methods, while the new procedures are also applied to real data from the financial market.     

Threats,chances and opportunities: social capital in Europe in times of social and economic hardship

The 2008 financial and economic crisis, characterized by an economic breakdown unparalleled since the Great Depression, provides a unique opportunity to study the relationships between economic developments and social capital by asking: How does social capital change in times of social and economic hardship? In order to explore the trends of social capital development, data from the European Social Survey 2002–2016 are used. The results suggest that economic decline – particularly increasing unemployment – is associated with a decline in social capital, especially in southern European countries. Furthermore, increasing long-term interest rates as an indicator of government future debt sustainability appear to be detrimental for social capital development. The impact of economic decline, however, appears to be contingent upon the functioning of state institutions: especially in countries characterized by well-functioning governments social capital is significantly less affected by economic decline than other countries.     

Does Facebook increase political participation? Evidence from a field experiment

During the last decade, much of political behaviour research has come to be concerned with the impact of the Internet, and more recently social networking sites such as Facebook, on political and civic participation. Although existing research generally finds a modestly positive relationship between social media use and offline and online participation, the majority of contributions rely on cross-sectional data, so the causal impact of social media use remains unclear. The present study examines how Facebook use influences reported political participation using an experiment. We recruited young Greek participants without a Facebook account and randomly assigned a subset to create and maintain a Facebook account for a year. In this paper we examine the effect of having a Facebook account on diverse modes of online and offline participation after six months. We find that maintaining a Facebook account had clearly negative consequences on reports of offline and online forms of political and civic participation.     

Traditional versus Secular Values and the Job–Life Satisfaction Relationship Across Europe

Using data from the European Values Survey (EVS), we examine the relationship between job and life satisfaction across Europe. We find that for the majority of employees job and life satisfaction are positively correlated, thus supporting the spillover hypothesis, whereby attitudes and practices developed in the life domain spill over into the work domain and vice versa. In contrast, we find little support for the compensation hypothesis, whereby employees who are dissatisfied in one domain seek compensatory rewards in the other domain. However, multivariate analysis reveals that the strength of the interaction between job and life satisfaction is mitigated by cultural values and interpersonal trust, as encapsulated in the ‘traditional versus secular values’ index reported in the EVS data. We thus find that predictors of the job–life satisfaction relationship vary across cultures and that such cross‐cultural variations are systematically related to salient cultural values and beliefs. The latter findings raise important questions about the universal application of existing theories in the subjective well‐being arena.     

Economic crisis and the employee: The effects of economic crisis on employee job satisfaction,commitment, and self-regulation

Greece has been suffering a severe crisis starting in about 2009. This paper examines the impact of the recent economic crisis in Greece on employee work-related attitudes via changes in regulatory focus. We collected data in a large and heterogeneous sample of employees (N = 1024) during the crisis and compared them with a matched sample of employees surveyed (N = 882) half a decade earlier, i.e., before the crisis. Participants reported their job satisfaction, organizational commitment and their self-regulatory focus. Results show, as expected, that participants after start of the crisis were lower in extrinsic job satisfaction, affective organizational commitment and were also (unexpectedly) lower in normative commitment, while these attitudinal changes were explained by decreased promotion orientation and increased prevention focus. Rather unexpectedly, pre-crisis and crisis samples did not differ in levels of continuance commitment. This paper makes a relevant contribution by showing that the threatening crisis event does not only have negative effects on work-related outcomes, but also that changes in regulatory foci occur and explain attitudinal change indicating an adaptive mechanism to the threatening situation of an economic crisis.     

Early Career Mobility and Earnings Profiles of German Apprentices: Theory and Empirical Evidence

We investigate how apprenticeship training affects the early career mobility and earnings profiles of young apprentices in Germany. The heterogeneous quality and nature (whether general or firm specific) of training across firms is expected to be reflected in the post‐apprenticeship mobility and earning patterns of young workers. In this paper, we argue that a simple model of training and labour turnover can explain such patterns. Specifically, assuming that job changes are associated with a loss of accumulated firm‐specific skills, the model predicts that although movers initially experience a productivity loss, their earnings grow at a faster rate than those of stayers. As job changes become more costly the longer a worker stays with the training firm, later movers experience a larger reduction in their earnings compared with direct movers. Estimated selectivity‐corrected earnings equations for movers and stayers, based on data from the German Socioeconomic Panel (GSOEP), support the predictions of the model and highlight important differences in earnings profiles and mobility patterns by apprenticeship firm size.     

Barriers and facilitators to adherence to group exercise in institutionalized older people living with dementia: a systematic review

Objectives

Research suggests targeted exercise is important for people living with dementia, especially those living in residential care. The aim of this review was to collect and synthesize evidence on the known barriers and facilitators to adherence to group exercise of institutionalized older people living with dementia.

Methods

We searched all available electronic databases. Additionally, we searched trial registries (clinicaltrial.gov, and WHO ICTRP) for ongoing studies. We searched for and included papers from January 1990 until September 2017 in any language. We included randomized, non-randomized trials. Studies were not eligible if participants were either healthy older people or people suffering from dementia but not living in an institution. Studies were also excluded if they were not focused on barriers and facilitators to adherence to group exercise.

Results

Using narrative analysis, we identified the following themes for barriers: bio-medical reasons and mental wellbeing and physical ability, relationships dynamics, and socioeconomic reasons. The facilitators were grouped under the following thematic frames: bio-medical benefits and benefits related to physical ability, feelings and emotions and confidence improvements, therapist and group relationships dynamics and activity related reasons.

Conclusions

We conclude that institutionalized older people living with dementia, even those who are physically frail, incontinent and/or have mild dementia can demonstrate certain level of exercise adherence, and therefore can respond positively to exercise programs. Tailored, individually-adjusted and supported physical activity, led by a knowledgeable, engaging and well communicating therapist/facilitator improves the adherence to group exercise interventions of institutionalized older people living with dementia.

     

Safe sets in graphs: Graph classes and structural parameters

A safe set of a graph \(G=(V,E)\) is a non-empty subset S of V such that for every component A of G[S] and every component B of \(G[V {\setminus } S]\), we have \(|A| \ge |B|\) whenever there exists an edge of G between A and B. In this paper, we show that a minimum safe set can be found in polynomial time for trees. We then further extend the result and present polynomial-time algorithms for graphs of bounded treewidth, and also for interval graphs. We also study the parameterized complexity. We show that the problem is fixed-parameter tractable when parameterized by the solution size. Furthermore, we show that this parameter lies between the tree-depth and the vertex cover number. We then conclude the paper by showing hardness for split graphs and planar graphs.